title: Phenylethenyl-substituted triphenylamines: efficient, easily obtainable, and inexpensive hole-transporting materials.
abstract: Star-shaped charge-transporting materials with a triphenylamine (TPA) core and various phenylethenyl side arm(s) were obtained in a one-step synthetic procedure from commercially available and relatively inexpensive starting materials. Crystallinity, glass-transition temperature, size of the π-conjugated system, energy levels, and the way molecules pack in the solid state can be significantly influenced by variation of the structure of these side arm(s). An increase in the number of phenylethenyl side arms was found to hinder intramolecular motions of the TPA core, and thereby provide significant enhancement of the fluorescence quantum yield of the TPA derivatives in solution. On the other hand, a larger number of side arms facilitated exciton migration through the dense side-arm network formed in the solid state and, thus, considerably reduces fluorescence efficiency by migration-assisted nonradiative relaxation. This dense network enables charges to move more rapidly through the hole-transport material layer, which results in very good charge drift mobility (μ up to 0.017 cm(2) V (-1) s(-1)).
authors.affiliation: Department of Organic Chemistry, Kaunas University of Technology, Radvilenu pl. 19, Kaunas, 50254 (Lithuania), Fax: (+370) 37-300152.
authors.forename: Tadas
authors.initials: T
authors.lastname: Malinauskas
authors.forename: Maryte
authors.initials: M
authors.lastname: Daskeviciene
authors.forename: Giedre
authors.initials: G
authors.lastname: Bubniene
authors.forename: Ieva
authors.initials: I
authors.lastname: Petrikyte
authors.forename: Steponas
authors.initials: S
authors.lastname: Raisys
authors.forename: Karolis
authors.initials: K
authors.lastname: Kazlauskas
authors.forename: Valentas
authors.initials: V
authors.lastname: Gaidelis
authors.forename: Vygintas
authors.initials: V
authors.lastname: Jankauskas
authors.forename: Robertas
authors.initials: R
authors.lastname: Maldzius
authors.forename: Saulius
authors.initials: S
authors.lastname: Jursenas
authors.forename: Vytautas
authors.initials: V
authors.lastname: Getautis
keywords: amorphous materials; fluorescence spectroscopy; ionization potentials; luminescence; semiconductors